First some remarks about the used terminology. "Call forwarding" is a feature under control of the called subscriber pB (the person B). Call forwarding means that if the called subscriber pB wants to receive calls over a terminal C different from the usual one he/she instructs the network accordingly and pB pays for the additional cost. As opposed to this, "redialing" means terminating a first call by going on-hook and then going off-hook again and re-performing dialing using a new number for dialing. Redialing is under control of the calling subscriber pA (the person A) and pA profits from any cost saving or pays for any additional cost resulting from the redialing. "Call redirecting" is used in the present text as a common designation for changes in call routing, independently of whether the responsible actor is the calling pA or the called pB subscriber.
It is the aim of modern telecommunication to provide universal mobility, i.e. to make it possible for roaming subscribers to communicate with each other from and to terminals in virtually any networks. A simple type of mobility has been provided for a long time through call forwarding features in wire-bound and mobile radio telecommunication networks, allowing calls to be received on an alternative terminal. More advanced mobility, but restricted to a certain area, has been provided by cellular radio systems, allowing calls to be received over a mobile radio terminal carried by the called subscriber. "Global" mobility has been described in the international published application WO94/05129, allowing in principle calls to be received in any mobile radio network all over the world.
However subscribers want to have even better mobility not only geographically but also between networks and easily select between terminals available e.g. cellular radio terminals, wire-bound terminals, personal computers, etc. for special communication needs and/or to minimise cost.